Variable: add #reject, #rejected? and raise in #wait

lib/async/variable.rb

@@ -30,24 +30,40 @@ def resolve(value = true)
 
 			condition.signal(value)
 		end
+
+		def reject(error)
+			@error = error
+			condition = @condition
+			@condition = nil
+
+			self.freeze
+
+			condition.signal # signal without value
+		end
 
 		# Alias for {#resolve}.
 		def value=(value)
 			self.resolve(value)
 		end
-		
+
 		# Whether the value has been resolved.
 		#
 		# @returns [Boolean] Whether the value has been resolved.
 		def resolved?
-			@condition.nil?
+			@condition.nil? && @error.nil?
+		end
+
+		def rejected?
+			@condition.nil? && !!@error
 		end
 
 		# Wait for the value to be resolved.
 		#
 		# @returns [Object] The resolved value.
+		# @raises [Exception] The error with which this Variable was rejected
 		def wait
 			@condition&.wait
+			raise @error if @error
 			return @value
 		end
 

test/async/variable.rb

@@ -21,13 +21,37 @@
 
 		variable.resolve(value)
 	end
+
+	it "can wait for the value to be resolved using setter" do
+		Async do
+			expect(variable.wait).to be == value
+		end
+
+		variable.value = value
+	end
 
 	it "can't resolve it a 2nd time" do
 		variable.resolve(value)
 		expect do
 			variable.resolve(value)
 		end.to raise_exception(FrozenError)
 	end
+
+	it "can reject with an exception" do
+		variable.reject RuntimeError.new("boom")
+		expect(variable).not.to be(:resolved?)
+		expect(variable).to be(:rejected?)
+	end
+
+	it "can wait for a rejection with an error" do
+		Async do
+			expect do
+				variable.wait
+			end.to raise_exception(RuntimeError)
+		end
+
+		variable.reject(RuntimeError.new)
+	end
 end
 
 include Sus::Fixtures::Async::ReactorContext